In the presented study the reaction of the assimilatory tissues of Norway spruce (Picea abies [L.] Karst.) and silver fir (Abies alba Mill.) to immission stress has been evaluated. A study method was used evaluating changes of epicuticular waxes which have above all a protective function and are damaged by immissions as the first, even before the damage to assimilatory tissues is visible. The reaction of these two tree species was monitored on two localities under a long-term air pollution load and on three control plots in regions free of air pollution. Epicuticular waxes of Norway spruce in the immission regions were damaged already with the first needle year-class, while those on the plots without immissions only after three years. In silver fir no damage to epicuticular waxes was found even in the regions under a long-term air pollution load. The structure and amount of epicuticular waxes of silver fir, compared to samples from the regions free of air pollution, did not differ. First negative changes occurred only after three years. The epicuticular waxes of silver fir (Abies alba Mill.) arc more resistant to the immission stress, compared to those of Norway spruce (Picea abies [L.] Karst.) and no destruction of them in the immission regions occurs as early as with the Norway spruce.